Antibodies to carcinoembryonic antigen (CEA) will be purified and labeled with radioactive iodine. In vivo studies will be carried out on patients with tumors, primarily colonic cancer, by presurgical injection of the labeled purified antibody. Scintillation scanning results and counting of surgical samples of normal and pathological tissue will be used to demonstrate localization of the preparation. It is hoped to be able to demontrate specificity of such labeled antiserum as well as its ability to concentrate in tumor. This can then be used as a diagnostic test for some types of tumors as well as determining sites of metastases. The antibody preparations will also be used to determine the presence or absence of CEA in various tumor tissues as well as normal organs. This will be done utilizing the binding of the isotopically labeled antibody to sections of tumor and normal tissue. Specific antibody to CEA as well as cross-reacting antigen will be prepared using specific antigens diazotized to glass beads as an immunoabsorbent.